1. Field of the Invention
Embodiments of the invention generally relate to one or more collection enhanced materials, flue gas additives, methods of making such, apparatuses for adding such when used with one or more units, and methods of using such in one or more units, such as fluidized units.
2. Description of the Related Art
FIG. 1 is a schematic diagram of a conventional fluid catalytic cracking system 130. The fluid catalytic cracking system 130 generally includes a fluid catalytic cracking (FCC) unit 100 coupled to a catalyst addition system 110, a petroleum feed stock source 104, an exhaust gas system 114, and a distillation system 116.
The FCC unit 100 includes a regenerator 150 and a reactor 152. The reactor 152 primarily houses the catalytic cracking reaction of the petroleum feed stock and delivers the cracked product in vapor form to the distillation system 116. Spent catalyst from the cracking reaction is transferred from the reactor 152 to the regenerator 150 to regenerate the catalyst by removing coke and other materials. The regenerated catalyst is then reintroduced into the reactor 152 to continue the petroleum cracking process. Exhaust gas from the regenerator 150 exits the FCC unit 100 through an exhaust path 108, traveling through the exhaust system 114 until exiting the exhaust system 114 to the environment through an exhaust flue 106.
The catalyst addition system 110 maintains a continuous or semi continuous addition of fresh base catalyst to the inventory circulating between a regenerator and a reactor. The catalyst addition system 110 generally includes a vessel 112 coupled to the FCC unit 100 by a feed line 118. An additive addition system 120 may also be utilized to maintain a continuous or semi continuous addition of fresh additives to the FCC unit 100, for example, for emission control. The additive addition system 120 is typically disposed near the catalyst addition system 110 and generally includes a vessel 122 coupled to the FCC unit 100 by the feed line 118.
During the catalytic cracking process, there is a dynamic balance of the total amount of the base cracking catalyst within the FCC unit and desire to maintain the activity level of the base cracking catalyst within the FCC unit. The amount of base cracking catalyst within the FCC unit may increase over time, which may result in the catalyst bed level within the regenerator reaching an upper operating limit. The catalyst bed level may reach an upper operating limit when the catalyst addition rate for maintenance of catalyst activity or level exceeds the lost catalyst and the excess catalyst is periodically withdrawn from the FCC unit. Conversely, the amount of base catalyst within the FCC unit may decrease significantly over time, causing the performance and desired output of the FCC unit to diminish, and in extreme cases the FCC unit may become inoperable. For example, fresh base cracking catalyst is periodically added to the FCC unit to replace base catalyst lost in various ways or to replenish base catalyst which has become deactivated over time. Catalyst and additives become fines (also called particulate matter and hereinafter referred to as “PM”) by attrition during gradual transfer to and from the reactor 152 and regenerator 150. Fines transfer more easily out of the FCC unit with the waste or product streams. Fines exiting the regenerator through the exhaust flue may be considered an environmental hazard. As such, one or more particle removal devices are typically utilized to prevent fines from exiting the exhaust flue. These particle removal devices may include third stage separators (TSS) and electrostatic precipitators (ESP). In many refineries, the ESP is the final device used to reduce the level of PM emitted to atmosphere from the FCC flue gas stream by absorbing PM.
To improve ESP collection of PM, a refiner generally increases the power to the ESP, and/or injects ammonia into or upstream of the ESP. Increased power usage is expensive and increases CO2 emissions Ammonia is effective, but excess ammonia can lead to ammonia emission through the flue stack, which is also under scrutiny as an environmental pollutant. Thus, increasing the efficiency of the ESP with ammonia is not considered a viable long term solution.
Additionally, refineries must also meet Environmental Protection Agency (EPA) SOx emissions regulations. However, low levels of SOx emissions in the FCC unit flue gas stream causes an increase in the emission of PM. Thus, as refineries try to reduce SOx emissions to meet environmental regulations, operating costs increase along with an increase in the amount of PM released to the environment through the flue stack.
Thus, a need exists for a cost effective way to meet EPA SOx emissions regulations without increasing PM emissions or increasing ammonia usage. A need also exists for collection enhanced materials, flue gas additives, methods of making such, apparatuses for adding such to one or more units, and methods of using such in one or more units, such as fluidized units.